Deutsch Intern
Prof. Dr. Holger Helten

Publications

69. J. Chorbacher, J. Klopf, A. Friedrich, M. Fest, J. S. Schneider, B. Engels, H. Helten,* Regioregular Poly(p-phenylene iminoborane): A Strictly Alternating BN-Isostere of Poly(p-phenylene vinylene) with Stimuli-Responsive Behavior, Angew. Chem. Int. Ed. 2024, e202416088  [DOI].
68. H. J. Sanderson, A. Helbig, G. Kociok-Köhn, H. Helten,* U. Hintermair,* Reversible formation of tetraphenylpentalene, a room temperature stable antiaromatic hydrocarbon, Chem. Sci. 2024, DOI: 10.1039/D4SC06439A.
67. J. Bachmann, A. Drichel, J. Klopf, A. Koner, A. Slabon,* H. Helten,* Bifuran- and bithio-phene-fused 4,6-dihydro-1,2,7-oxadiborepins as building blocks for conjugated copolymers, Org. Chem. Front. 2024, accepted.
66.

J. S. Schneider, H. Helten,* Hybrid materials comprising ferrocene and diaminoborane moieties: linear concatenation versus macrocyclization, Chem. Commun. 2024, 60, 11706–11709 [DOI]. (special collection: ChemComm 60th Anniversary Collection)

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65. N. A. Jenek, A. Helbig, S. M. Boyt, M. Kaur, H. J. Sanderson, S. B. Reeksting, G. Kociok-Köhn, H. Helten,* U. Hintermair,* Understanding and tuning the electronic structure of pentalenides, Chem. Sci. 2024, 15, 12765–12779 [DOI].
64. M. Maier, F. Brosge, J. S. Schneider, J. Bachmann, S. Schmidt, C. Bolm,* H. Helten,* Sulfur-Based Building Blocks in BN- and BO-Doped Inorganic–Organic Hybrid Polymers, Macromolecules 2024, 57, 6370−6378 [DOI].
63. F. Sturm, M, Bühler, C. Stapper, J. S. Schneider, H. Helten, I. Fischer,* M. I. S. Röhr,*  Impact of isoelectronic substitution on the excited state processes in polycyclic aromatic hydrocarbons: a joint experimental and theoretical study of 4a,8a-azaboranaphthalene, Phys. Chem. Chem. Phys. 2024, 26, 7363−7370  [DOI] ("Hot Paper").
62.

M. Maier, A. Friedrich, J. S. Schneider, J. A. P. Sprenger, J. Klopf, L. Fritze, M. Finze, H. Helten,* Poly(iminoborane)s with Aromatic Side Groups: Insights into the Microstructure from Monodisperse Model Oligomers, ChemistryEurope 2024, 2, e202300085 [DOI].

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61. M. Müller, H. Neitz, C. Höbartner,* H. Helten,* BN-Phenanthrene- and BN-Pyrene-Based Fluorescent Uridine Analogues, Org. Lett. 2024, 26, 1051–1055 [DOI].
60.

M. Maier, V. Zeh, N. Munker, J. Glock, K. Oberdorf, O. Ayhan, C. Lichtenberg, H. Helten,* 1,2,5-Azadiborolane as a Building Block for Inorganic–Organic Hybrid Polymers, Eur. J. Inorg. Chem. 2024, 27, e202300490 [DOI].

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59.

V. Zeh, J. S. Schneider, J. Bachmann, I. Krummenacher, H. Braunschweig, H. Helten,* Poly(ferrocenylene iminoborane): an inorganic–organic hybrid polymer comprising a backbone of moderately interacting ferrocenes, Chem. Commun. 2023, 59, 13723–13726 [DOI].
58.

M. Maier, J. Chorbacher, A. Hellinger, J. Klopf, J. Günther, H. Helten,* Poly(arylene iminoborane)s, Analogues of Poly(arylene vinylene) with a BN-Doped Backbone: A Comprehensive Study, Chem. Eur. J. 2023, 29, e202302767 [DOI] ("Hot Paper").

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57. H. Helten,* R. Waterman,* In Honor of Prof. Dr. Dr. hc Rainer Streubel, Eur. J. Inorg. Chem. 2023, 26, e202300425 [DOI].
56. J. S. Schneider, I. Krummenacher, H. Braunschweig, H. Helten,* Linear and macrocyclic oligo(p-phenylene iminoboranes) with ferrocenyl side groups – observation of selective, non-templated macrocyclization, Chem. Commun. 2023, 59, 8408–8411, [DOI] (special issue: Pioneering Investigators Collection 2023, invited).
55. J. Chorbacher, M. Maier, J. Klopf, M. Fest, H. Helten,* Poly(thiophene iminoborane): A Poly(thiophene vinylene) (PTV) Analogue with a Fully B=N‐Doped Backbone, Macromol. Rapid Commun. 2023, 44, 2300278, [DOI].
54. J. Bachmann, A. Helbig, M. Crumbach, I. Krummenacher, H. Braunschweig, H. Helten,* Fusion of Aza- and Oxadiborepins with Furans via a Reversible Ring Opening Process Furnishes Versatile Building Blocks for Extended π-Conjugated Materials, Chem. Eur. J. 2022, 28, e202202455 [DOI].
53. S. Hagspiel, F. Fantuzzi, M. Arrowsmith, A. Gärtner, M. Fest, J. Weiser, B. Engels, H. Helten, H. Braunschweig,* Modulation of the Naked-eye and Fluorescence Colour of a Protonated Boron-doped Thiazolothiazole by Anion-dependent Hydrogen Bonding, Chem. Eur. J. 2022, 28, e202201398 [DOI].
52. M. Maier, J. Klopf, C. Glasmacher, F. Fantuzzi, J. Bachmann, O. Ayhan, A. Koner, B. Engels,* H. Helten,* Electrophilic activation of difunctional aminoboranes: B–N coupling versus intramolecular Cl/Me exchange, Chem. Commun. 2022, 58, 4464–4467  [DOI] (themed collection: Boron Chemistry in the 21st Century: From Synthetic Curiosities to Functional Molecules).
51. S. Fuchs, A. Jayaraman, I. Krummenacher, L. Haley, M. Baštovanović, M. Fest, K. Radacki, H. Helten, H. Braunschweig,* Diboramacrocycles: reversible borole dimerisation—dissociation systems, Chem. Sci. 2022, 13, 2932–2938 [DOI].
50. H. Helten,* "Organoboron and Related Group 13 Polymers", in Comprehensive Organometallic Chemistry IV (Eds.: D. O’Hare, K. Meyer, G. Parkin), Elsevier, New York, 2022, pp. 71–134 [DOI].
49.

M. Crumbach, J. Bachmann, L. Fritze, A. Helbig, I. Krummenacher, H. Braunschweig, H. Helten,* Dithiophene-Fused Oxadiborepins and Azadiborepins: A New Class of Highly Fluorescent Heteroaromatics, Angew. Chem. Int. Ed. 2021, 60, 9290–9295 [DOI]; Angew. Chem. 2021, 133, 9376–9381 [DOI] ("Hot Paper").

Highlighted in: "BRB, Looking for Aromaticity", T. M. Swager, M. Chen, Synfacts 2021, 17, 0392 [DOI].
48. M. Crumbach, O. Ayhan, L. Fritze, J. A. P. Sprenger, L. Zapf, M. Finze, H. Helten,* BNB-Doped phenalenyls – aromaticity switch upon one-electron reduction, Chem. Commun. 2021, 57, 2408–2411 [DOI].
47. F. Schorr, N. Schopper, N. Riensch, F. Fantuzzi, M. Neder, R. D. Dewhurst, T. Thiess, T. Brückner, K. Hammond, H. Helten, M. Finze, H. Braunschweig,* Controlled Synthesis of Oligomers Containing Main-Chain B(sp2)-B(sp2) Bonds, Chem. Eur. J. 2021, 27, 16043–16048  [DOI].
46. L. Fritze, M. Fest, A. Helbig, T. Bischof, I. Krummenacher, H. Braunschweig, M. Finze, H. Helten,* Boron-Doped α‑Oligo- and Polyfurans: Highly Luminescent Hybrid Materials, Color-Tunable through the Doping Density, Macromolecules 2021, 54, 7653–7665  [DOI].
45. L. Hahn, L. Keßler, L. Polzin, L. Fritze, S. Forster, H. Helten, R. Luxenhofer,* ABA Type Amphiphiles with Poly(2-benzhydryl-2-oxazine) Moieties: Synthesis, Characterization and Inverse Thermogelation, Macromol. Chem. Phys. 2021, 2100114 [DOI].
44. N. A. Riensch, L. Swoboda, A. Lik, I. Krummenacher, H. Braunschweig, H. Helten,* Con­jugated Bis(triarylboranes) with Disconnected Conjugation, Z. Anorg. Allg. Chem. 2021, 647, 421–424 [DOI].
43. N. A. Riensch, M. Fest, L. Fritze, A. Helbig, I. Krummenacher, H. Braunschweig, H. Helten,* Bifuran-bridged bisboranes: highly luminescent B-doped oligohetarenes, New J. Chem. 2021, 45, 14920–14924 [DOI].
42. T. Beweries,* H. Helten,* Poly(aminoborane)s & Poly(iminoborane)s, Encyclopedia of Inorganic and Bioinorganic Chemistry (Ed.: R. A. Scott), Wiley, Chichester, 2020, [DOI].
41. F. Brosge, T. Lorenz, H. Helten,* C. Bolm,* BN- and BO-Doped Inorganic—Organic Hybrid Polymers with Sulfoximine Core Units, Chem. Eur. J. 2019, 25, 12708–12711 [DOI] ("Hot Paper").
40. H. Helten,* Doping the Backbone of π-Conjugated Polymers with Tricoordinate Boron: Synthesis Strategies and Emerging Applications, Chem. Asian J. 2019, 14, 919—935 [DOI] (Minireview, invited).
39. L. Fritze, N. A. Riensch, H. Helten,* Catalytic Si/B Exchange Condensation: A Green B—C Coupling Method That Provides Access to Monodisperse (Het)arylborane "Trimers", Synthesis 2019, 51, 399—406 [DOI] (Feature Article, invited).
38. A. Lik, S. Jenthra, L. Fritze, L. Müller, K.-N. Truong, H. Helten,* From Monodisperse Thienyl- and Furylborane Oligomers to Polymers — Modulating the Optical Properties Through the Hetarene Ratio, Chem. Eur. J. 2018, 24, 11961—11972 [DOI] ("Very Important Paper", special issue: 7th EuCheMS Chemistry Congress, Liverpool).

37.

 N. A. Riensch, L. Fritze, T. Schindler, M. Kremer, H. Helten,* Difuryl(supermesityl)borane: a versatile building block for extended π-conjugated materials, Dalton Trans. 2018, 47, 10399—10403 [DOI] (special issue: New Talent: Europe, invited).
36. O. Ayhan, N. A. Riensch, C. Glasmacher, H. Helten,* Cyclolinear Oligo- and Poly(iminoborane)s: The Missing Link in Inorganic Main Group Macromolecular Chemistry, Chem. Eur. J. 2018, 24, 5883—5894 [DOI] ("Hot Paper").

Highlighted in: ChemistryViews [DOI].

Highlighted in: "Trendbericht Anorganische Chemie: Hauptgruppenelemente", C. Hering-Junghans, C. Sindlinger, Nachr. Chem. 2019, 67, 46—64 [DOI].
35. A. Lik, D. Kargin, S. Isenberg, Z. Kelemen,* R. Pietschnig,* H. Helten,* PBP bridged [3]ferrocenophane: a bisphosphanylborane with a redox trigger, Chem. Commun. 2018, 54, 2471—2474 [DOI].

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34. N. A. Riensch, A. Deniz, S. Kühl, L. Müller, A. Adams, A. Pich,* H. Helten,* Borazine-based inorganic—organic hybrid cyclomatrix microspheres by silicon/boron exchange precipitation polycondensation, Polym. Chem. 2017, 8, 5264—5268 [DOI].

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33. A. Lik, L. Fritze, L. Müller, H. Helten,* Catalytic B—C Coupling by Si/B Exchange: A Versatile Route to π-Conjugated Organoborane Molecules, Oligomers, and Polymers, J. Am. Chem. Soc. 2017, 139, 5692—5695 [DOI].
32. T. Lorenz, M. Crumbach, T. Eckert, A. Lik, H. Helten,* Poly(p-phenylene iminoborane): A Boron—Nitrogen Analogue of Poly(p-phenylene vinylene), Angew. Chem. Int. Ed. 2017, 56, 2780—2784 [DOI]; Angew. Chem. 2017, 129, 2824—2828 [DOI] ("Hot Paper").

Highlighted in: "Iminoborane units add inorganic flavor to polymers", S. K. Ritter, Chem. Eng. News 2017, 95(8), 11 [DOI].
31. H. Helten,* O. Ayhan, T. Lorenz, Bor und Stickstoff statt Kohlenstoff, Nachr. Chem. 2017, 65, 535—541 [DOI].
30. H. Helten,* Conjugated Inorganic—Organic Hybrid Polymers, Encyclopedia of Inorganic and Bioinorganic Chemistry (Ed.: R. A. Scott), Wiley, Chichester, 2017, [DOI].
29. O. Ayhan, T. Eckert, F. A. Plamper, H. Helten,* Poly(iminoborane)s: An Elusive Class of Main Group Polymers?, Angew. Chem. Int. Ed. 2016, 55, 13321—13325 [DOI]; Angew. Chem. 2016, 128, 13515—13519 [DOI].
28. T. Lorenz, A. Lik, F. A. Plamper, H. Helten,* Dehydrocoupling and Silazane Cleavage Routes to Organic—Inorganic Hybrid Polymers with NBN Units in the Main Chain, Angew. Chem. Int. Ed. 2016, 55, 7236—7241 [DOI]; Angew. Chem. 2016, 128, 7352—7357 [DOI].

Highlighted in: "A New Route to Polymers with NBN Backbone", T. M. Swager, Q. Zhang, Synfacts 2016, 12, 0691 [DOI].

Highlighted in: "Trendbericht Makromolekulare Chemie 2016", M. Sommer, F. Wurm, Nachr. Chem. 2017, 65, 348—358 [DOI].
27. H. Helten,* B=N Units as Part of Extended π-Conjugated Oligomers and Polymers, Chem. Eur. J. 2016, 22, 12972—12982 [DOI] (Concept Article, invited).
26. A. P. M. Robertson, E. M. Leitao, T. Jurca, M. F. Haddow, H. Helten,* G. C. Lloyd-Jones,* I. Manners,* Mechanisms of the Thermal and Catalytic Redistributions, Oligomerizations, and Polymerizations of Linear Diborazanes, J. Am. Chem. Soc. 2013, 135, 12670—12683 [DOI].
25. H. Helten, B. Dutta, J. R. Vance, M. E. Sloan, M. F. Haddow, S. Sproules, D. Collison, G. R. Whittell, G. C. Lloyd-Jones, I. Manners, Paramagnetic Titanium(III) and Zirconium(III) Metallocene Complexes as Precatalysts for the Dehydrocoupling/Dehydrogenation of Amine—Boranes, Angew. Chem. Int. Ed. 2013, 52, 437—440; Angew. Chem. 2013, 125, 455—458 ("Very Important Paper").
24. E. M. Leitao, N. E. Stubbs, A. P. M. Robertson, H. Helten, R. J. Cox, G. C. Lloyd-Jones, I. Manners, Mechanism of Metal-Free Hydrogen Transfer between Amine—Boranes and Aminoboranes, J. Am. Chem. Soc. 2012, 134, 16805—16816.
23. V. Blackstone, S. Pfirrmann, H. Helten, A. Staubitz, A. Presa Soto, G. R. Whittell, I. Manners, A Cooperative Role for the Counteranion in the PCl5-Initiated Living, Cationic Chain Growth Polycondensation of the Phosphoranimine Cl3P=NSiMe3, J. Am. Chem. Soc. 2012, 134, 15293—15296.
22. H. Helten, A. P. M. Robertson, A. Staubitz, J. R. Vance, M. F. Haddow, I. Manners, “Spontaneous” Ambient Temperature Dehydrocoupling of Aromatic Amine—Boranes, Chem. Eur. J. 2012, 18, 4665—4680.
21. J. Marinas Pérez, H. Helten, G. Schnakenburg, R. Streubel, A Novel Approach to 1,3,4-Dioxaphospholane Complexes: Acid-Induced Ring Expansion of an Oxaphosphirane Complex. The Problem of Construction and Deconstruction of O,P-Heterocycles, Chem. Asian J. 2011, 6, 1539—1545.
20. H. Helten, G. Schnakenburg, J. Daniels, A. J. Arduengo, III, R. Streubel, When Sterics Overcome Electronics: An Unusual Haptotropic P→N Pentacarbonyltungsten Shift, Organometallics 2011, 30, 84—91.
19. H. Helten, G. Schnakenburg, R. Streubel, Click Reactions of 2H-Azaphosphirene Chromium and Molybdenum Complexes and a Surprisingly Facile Access to a 2H-1,4,2-Diazaphosphole Derivative, Polyhedron 2011, 30, 1799—1805.
18. J. Marinas Pérez, H. Helten, B. Donnadieu, C. A. Reed, R. Streubel, Protonation-Induced Rearrangement of an Oxaphosphirane Complex, Angew. Chem. Int. Ed. 2010, 49, 2615—2618; Angew. Chem. 2010, 122, 2670—2674.
17. J. Marinas Pérez, C. Albrecht, H. Helten, G. Schnakenburg, R. Streubel, Competing ring cleavage of transient O-protonated oxaphosphirane complexes: 1,3-oxaphospholane and η2-Wittig ylide complex formation, Chem. Commun. 2010, 46, 7244—7246.
16. R. Streubel, J. Marinas Pérez, H. Helten, J. Daniels, M. Nieger, Developing click reactions of a 3-ferrocenyl-2H-azaphosphirene complex, Dalton Trans. 2010, 39, 11445—11450.
15. S. Fankel, H. Helten, G. von Frantzius, G. Schnakenburg, J. Daniels, V. Chu, C. Müller, R. Streubel, Novel access to azaphosphiridine complexes and first applications using Brønsted acid-induced ring expansion reactions, Dalton Trans. 2010, 39, 3472—3481.
14. H. Helten, M. Beckmann, G. Schnakenburg, R. Streubel, Synthesis and Reactivity of an Unusual Ferrocenophane Bis(carbene complex), Eur. J. Inorg. Chem. 2010, 2337—2341.
13. H. Helten, J. Daniels, M. Nieger, R. Streubel, Extended π conjugation in 2H-1,4,2-diazaphosphole complexes, New J. Chem. 2010, 34, 1593—1602.
12. H. Helten, M. Engeser, D. Gudat, R. Schilling, G. Schnakenburg, M. Nieger, R. Streubel, Protonation of 2H-Azaphosphirene Complexes: P—N Bond Activation and Ring-Expansion Reactions, Chem. Eur. J. 2009, 15, 2602—2616.
11. H. Helten, J. Marinas Pérez, J. Daniels, R. Streubel, First Brønsted Acid-Induced Ring Expansion of an Oxaphosphirane Complex: A Combined Experimental and DFT Study, Organometallics 2009, 28, 1221—1226.
10. H. Helten, S. Fankel, O. Feier-Iova, M. Nieger, A. Espinosa Ferao, R. Streubel, Strong Evidence for an Unprecedented Borderline Case of Dissociation and Cycloaddition in Open-Shell 1,3-Dipole Chemistry: Transient Nitrilium Phosphane-Ylide Complex Radical Cations, Eur. J. Inorg. Chem. 2009, 3226—3237.
9. H. Helten, G. von Frantzius, G. Schnakenburg, J. Daniels, R. Streubel, How To Tune Acid-Induced Ring Enlargement Reactions — The Strange Case of 2H-Azaphosphirene Complexes and Its Surprising Dichotomy, Eur. J. Inorg. Chem. 2009, 2062—2065.
8. R. Streubel, M. Beckmann, C. Neumann, S. Fankel, H. Helten, O. Feier-Iova, P. G. Jones, M. Nieger, Synthesis, Structure, and Ring-Expansion Reactions of a 3-Ferrocenyl-Substituted 2H-Azaphosphirene Tungsten Complex, Eur. J. Inorg. Chem. 2009, 2090—2095.
7. H. Helten, C. Neumann, A. Espinosa, P. G. Jones, M. Nieger, R. Streubel, Evidence for Ligand-Centered Reactivity of a 17e Radical Cationic 2H-Azaphosphirene Complex, Eur. J. Inorg. Chem. 2007, 4669—4678.
6. R. Vicik, H. Helten, T. Schirmeister, B. Engels, Rational Design of Aziridine-Containing Cysteine Protease Inhibitors with Improved Potency: Studies on Inhibition Mechanism, ChemMedChem 2006, 1, 1021—1028.
5. H. Helten, T. Schirmeister, B. Engels, Theoretical Studies about the Influence of Different Ring Substituents on the Nucleophilic Ring Opening of Three-Membered Heterocycles and Possible Implications for the Mechanisms of Cysteine Protease Inhibitors, J. Org. Chem. 2005, 70, 233—237.
4. H. Helten, T. Schirmeister, B. Engels, Model Calculations about the Influence of Protic Environments on the Alkylation Step of Epoxide, Aziridine, and Thiirane Based Cysteine Protease Inhibitors, J. Phys. Chem. A 2004, 108, 7691—7701.
3. P. W. Musch, C. Remenyi, H. Helten, B. Engels, On the Regioselectivity of the Cyclization of Enyne-Ketenes: A Computational Investigation and Comparison with the Myers-Saito and Schmittel Reaction, J. Am. Chem. Soc. 2002, 124, 1823—1828.
2. B. Walfort, T. Auth, B. Degel, H. Helten, D. Stalke, Copper and Silver Triimidosulfites: S(NtBu)32--Bicapped M3-Triangles Connected via Lithium Halide Ladders or Fragments Thereof, Organometallics 2002, 21, 2208—2214.
1. M. Schmittel, J.-P. Steffen, M. Maywald, B. Engels, H. Helten, P. Musch, Ring size effects in the C2—C6 biradical cyclisation of enyne-allenes and the relevance for neocarzinostatin, J. Chem. Soc., Perkin Trans. 2 2001, 1331—1339.

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